Read these:
http://www.droidforums.net/forum/galaxy-nexus-general-discussions/188043-battery-drains-fast.html
Android OS killing battery - xda-developers
Today's battery life - RootzWiki
And finally, here's a write up that was actually done for the Bionic, but most of it applies to the Gnex (one strong note - the part about a Factory Reset is very different on the Gnex, you must copy all things on the "sdcard section" to your computer as the Factory Reset will wipe everything):
If you are having short battery life here’s a list of things that can help. Just read through the list and select the items that fit with the way you want to use your phone. Not all items will work for everyone and this list was written for the Droid Bionic but should work for your phone too:
- Don't use an automatic task killer--not even the one that comes with the phone. Reboot your phone and look at what's running. If anything that you've installed is running and there's no reason for it, then uninstall it and find an alternative that behaves. Ignore any stock apps that run on boot as I've found them to be more or less benign.
- Weather widgets, live wallpapers, news/social feeds, any app or service that you use that runs--do without it if you can. If you can’t do without it, lengthen it’s refresh time.
- Don't use antivirus
- Set your WIFI sleep policy to never. The default is "turn off when screen turns off". This will cause the wifi to reconnect every time you open the phone. From any Home Screen select Menu/Settings/Wireless & Networks/ and then use the Menu button to see some new options - select Advanced. Then select Wifi Sleep Policy and set it to Never. Home key to return to Home Screen.
- If you have access to wifi, leave it toggled on as it is more efficient than 3G. Wifi consumes less battery power than 3G.
- I leave GPS toggled on too by the way. Apps use it as needed. When I'm done with Maps or an app that uses it, I'm sure to return to the home screen so GPS can stop. Under wireless settings turn on "Google location services" so that an app is able to use network resources to get your location instead of GPS. I have "VZW location services" turned off--don't know why that option is even there. By the way, I increase the speed of voice output > text to speech > speech rate because I like the directions to get spit out faster. That saves a bit of battery. Turning off the display and just listening for directions help. Also, often I just get the directions and then exit back to the home screen: GPS uses so much battery I try to get it over with ASAP.
- When you get a 1) new battery, 2) do a factory reset, or 3) an OS upgrade - run your battery all the way down until the phone shuts off and then charge the battery all the way up. This will calibrate the phone's understanding of the battery's capacity. Do this once every month or two also, but don't do it too often if you can help it.
- I have my battery set to "Performance Mode" and data is on all the time because I am on call 24x7. If you don't mind, try out a more conservative battery profile to save more gobs of energy.
- Set screen brightness to "Automatic"
- Under Accounts, click on any account listed and turn off sync for any items that you're not interested in syncing. For example, Google Books if you don't use it. Don't use Backup Assistant--I prefer syncing my contacts with Google. You don't need both. Also go into your contacts > menu > display options > backup assistant > UNCHECK. Also do contacts > menu > more > settings > contact storage > and select your Google account and "remember this choice"
- Turn on Bluetooth only when you are going to use it.
- Consider turning off voice privacy. This may not be a big deal but it will save some processing (and therefore battery). It may also improve call quality.
-Turn off haptic feedback, animations, and any un-needed sounds in Android settings and in your apps
- Set your screen timeout to as low a time as you can stand (I use 1 minute) and manually turn the screen off when you’ve finished using the phone.
- Turn off in-pocket detection. In-Pocket Detection has been the source of many issues already.
- Keyboard: turn off vibrate on key press and sounds for any keyboards you use
- Use a red or black screen background. On the original Droid screen--not sure about this Bionic screen--red was the most efficient color that could be displayed.
- Camera app: I like keeping location on and flash on auto. Consider turning location off or at least returning to the home screen ASAP when using camera if location for camera is on.
- In stock browser the default home page is Google and it uses your location. This is a bad idea as it can waste your battery for no reason. Make something else your home page and make sure to close any web page that uses your location when you're done viewing it.
- Charge your phone via the wall charger instead of computer USB as it is faster. Also, don't use long USB cords--use regular power extension cords instead. I stick with the charger that came with the phone. Put the phone on charger when you go to bed every night.
- Consider install the Home Replacement app Zeam. It is basic app that uses very few resources and will help with battery power.
- Emails: I don't know what email app you use, but try this. It saves battery power and in some cases emails arrive quicker. This scheme will have you using only the Gmail app on the phone for all email accounts whether they are pop3 accounts or Gmail.
- If you are using Live Wall Papers, stop!
------------------------------------------------------------------------------------------------------------------
This is a link to some very good videos about saving battery power on the Bionic (there are 4 parts and the other parts will show up as available videos when part 1 finishes):
Battery Saving Video
Part 1: [video=youtube;cvWg7SbUgsI]http://www.youtube.com/watch?feature=player_embedded&v=cvWg7SbUgsI[/video]
If battery life is still bad: Consider doing a factory reset: These have gotten pretty painless lately by following these simple steps: 1. Make sure Backup and Restore are checked in the Privacy setting. 2. When going through the setup after the reset, turn on wifi as soon as you can (assuming it is available). 3. After you have entered your Gmail account info, you will be presented with a screen that has two check boxes. Basically they are "Do you want Google to backup and restore this phone”. Make sure you check both of those. Your apps will then automatically reinstall (paid and free). Set the phone aside for a minute or two and let the apps download and install. 3. If rooted, use an app such as titanium backup to restore data only to select apps such as Tapatalk and you will not have to re-enter all your login information. I do this for 3-4 apps (Tapatalk, SPB Shell, etc.).
I've been flashing new roms/updates about once per day lately and I can be up and running with all my apps and settings back in place in less than 20 minutes. It's pretty painless now.
